The present invention relates to videotape cassettes containing magnetic tapes. More particularly, the present invention concerns a tape guide that is adapted to be positioned on the interior of the videotape cassette for guiding the magnetic tape as it passes from spool to spool.
Tape guides are a necessary part of every videotape cassette in order to ensure that the tape is properly guided and fed to the access opening at the front edge of the videotape cassette when the cassette is inserted into the tape deck for playing. The number of tape guides produced annually in order to meet the needs of the magnetic tape cassette manufacturing industry is enormously large. At the very least, the number of tape guides produced annually is in the neighborhood of several hundred million. Thus, it can be readily seen that any cost reduction that can be achieved with respect to the manufacture of a single tape guide can result in significant overall cost savings when considered in light of the total number of tape guides manufactured.
Typically, a hollow stand-alone tape guide for use in a videotape cassette is manufactured from stainless steel having a thickness of approximately 0.021-0.022 inches and in some cases, as thin as 0.015 inches. After the tape guide has been manufactured from the aforementioned material, it is subjected to chemical treatment as well as polishing and finishing operations in order to ensure that the exterior finish on the tape guides is smooth and free of any burrs or other foreign material and so smooth that it does not adversely affect magnetic tape sliding on its surface.
The magnetic tape contained in the videotape cassette is made of a highly sensitive material that can be very easily damaged through contact with rough surfaces and the like. Thus, the aforementioned chemical treatment and polishing and finishing operations are necessary in order to produce a tape guide whose exterior surface has a very high quality finish. In that way, the magnetic tape that passes around the tape guide will not become damaged as a result of contact with burrs or other types of foreign objects located on the exterior surface of the tape guide.
The finish required on the exterior surface of the tape guide, otherwise described as the surface roughness, can be expressed numerically in microinches. The numerical designation represents the arithmetic average deviation of the exterior surface from the mean line in a profile. The desired roughness for the exterior surface of a tape guide for use in guiding the magnetic tape in a videotape cassette should preferably be about eight microinches. It is rather evident that such a smooth, high quality surface finish requires extensive chemical treatment and finishing and polishing which can significantly increase the cost associated with producing the tape guide.
From the foregoing discussion, it can be seen that it would be highly desirable to manufacture a tape guide for use in a videotape cassette that possesses all of the necessary physical properties and structural features required of the tape guide but which is thinner. The manufacture of a thinner tape guide would permit the realization of substantial cost savings.
The manufacture of a tape guide from thinner material does, however, raise a concern that when the tape guide interacts with another tape guide such as during chemical treatment, polishing, finishing or handling of the tape guide, the two tape guides will become interlocked with one another. When a tape guide is manufactured as a one piece unit with a slit extending longitudinally along its length, a gap is formed in the unit as a result of the slit. In prior art stand-alone tape guides, the thickness of the material used to manufacture the tape guides was greater than the width of the gap. Hence, it was quite unlikely that one tape guide would become interlocked with another tape guide because the tape guide was not thin enough to fit into the gap formed by the slit.
However, the manufacture of a tape guide from much thinner material raises the possibility that the tape guide will become interlocked with another tape guide during the finishing, chemical treatment and handling of the tape guide because the thickness of the material is less than the width of the gap in the tape guide formed by the slit. Since the thickness of the material used to manufacture the tape guide is less than the width of the gap formed by the slit, it is highly probable that while the tape guide is interacting with other tape guides, one tape guide will be pushed into the slit in another tape guide to thereby result in the two tape guides becoming interlocked with one another.
The problems resulting from interlocked tape guides are readily apparent. The time and cost associated with attempting to separate the interlocked tape guides are highly undesirable. Further, in light of the smooth and high quality exterior finish that is required of the tape guides in order to avoid damaging the magnetic tape, there exists the possibility that the interlocking of two tape guides will cause damage to the exterior surface of the tape guides. Similar damage may result from any attempt to separate the tape guides after they have become interlocked.
It can be seen from the foregoing discussion that there exists a need in the art for a tape guide that is manufactured from thinner material so as to be less expensive. It is further apparent that there exists a need for a thinner, less expensive tape guide that is not susceptible to becoming interlocked with other tape guides.
The aforementioned problems are overcome and the foregoing objectives are achieved by the tape guide according to the present invention. The tape guide includes a substantially tubular, longitudinally extending member having first and second oppositely located ends and having interior and exterior surfaces. A slit extends along the entire length of the substantially tubular member to define first and second spaced apart and facing edge faces. An arrangement is attached to the substantially tubular member for inhibiting other tape guides from extending through the slit and becoming interlocked with the substantially tubular member. A groove can be located in each end of the substantially tubular member for properly orienting the tap guide when it is positioned in the magnetic tape cassette.
One embodiment of the arrangement for inhibiting other tape guides from extending through the slit in the cylindrical member includes a plurality of first tabs connected to the first edge face of the substantially tubular member and extending toward the second edge face and a plurality of second tabs connected to the second edge face of the substantially tubular member and extending towards the first edge face. Each one of the first tabs overlaps one of the second tabs and slots are provided adjacent the first tabs for slidably receiving the second tabs while slots are provided adjacent the second tabs for slidably receiving the first tabs.
An additional embodiment of the arrangement for inhibiting another tape guide from extending through the slit in the cylindrical member includes outdented portions extending from the first edge face that are positioned opposite to indented portions in the second edge face and outdented portions extending from the second edge face that are positioned opposite to indented portions in the first edge face.